Nice spreadsheet!

As for weighing the packs, step on the bathroom scale and weigh yourself. Next don the pack and re-weigh again, you can now figure out the weight of the pack.

When I do this, I only count the lb weight not the ounces of the pack overall. The way I look at it, a few ounces out on the pack weight is not going to break me...I'll just have to eat a few less Timbits !